feat: implement AttractVideoPlayer (#2)

Service Button : Pause the attract video
L2/L3 Buttons : Previous/next to cycle through all the attract videos
Saving the selected video for future game launches

Co-authored-by: akanyan <alicechecker01@proton.me>
Reviewed-on: akanyan/mu3-mods#2
Co-authored-by: jujuforce <jujuforce@noreply.gitea.tendokyu.moe>
Co-committed-by: jujuforce <jujuforce@noreply.gitea.tendokyu.moe>

AttractVideoPlayer/MU3/patch_AdvManager.cs

@@ -0,0 +1,35 @@
+using MU3.Operation;
+using MU3.Util;
+using UnityEngine;
+
+namespace MU3;
+
+class patch_AdvManager: AdvManager {
+    private GameObject objMovie;
+    private CriManaMovieMaterial movieController;
+
+    private extern bool orig_exec();
+    public new bool exec() {
+        if(movieController?.player?.status == CriMana.Player.Status.Playing) {
+            if(Singleton<UIInput>.instance.getTriggerOn(UIInput.Key.Service)) {
+                movieController.player.Pause(!movieController.player.IsPaused());
+            } else if(Singleton<UIInput>.instance.getTriggerOn(UIInput.Key.L2)) {
+                addMovieOffset(-1);
+            } else if(Singleton<UIInput>.instance.getTriggerOn(UIInput.Key.L3)) {
+                addMovieOffset(1);
+            }
+        }
+
+        return orig_exec();
+    }
+    public void addMovieOffset(int offset) {
+        var om = (patch_OperationManager)Singleton<OperationManager>.instance;
+        om.MovieIndex += offset;
+
+        movieController.Stop();
+        Utility.destroyGameObject(ref movieController);
+        Utility.destroyGameObject(ref objMovie);
+
+        initMovie();
+    }
+}